1. Field of the Invention
The present invention relates to the transmission of video data in a wireless network, and more particularly, to a data transmission method and apparatus efficiently using the resources of a wireless network at the time of transmission of video data.
2. Description of the Related Art
With the development and popularization of wireless communication technologies such as Institute of Electrical and Electronic Engineers (IEEE) 802.11a/b/g, Code Division Multiple Access (CDMA) 2000, Universal Mobile Telecommunications System (UMTS), and Wireless Broadband (WiBro), it is expected that home networks and the wireless Internet will be used widely. It is also expected that video streaming will be the killer application for these services. More particularly, as a broadcasting system, such as Digital Multimedia Broadcasting (DMB), is constructed, the importance of video streaming in wireless communication has become greater.
In the wireless network, packets are frequently lost because of unstable channel conditions. This may cause a problem with video quality on a receiving side.
To eliminate the video quality problem on a user side, a method of retransmitting lost packets or retransmitting packets at a slow transfer rate has been conventionally used. In more detail, if the transmission of a specific packet fails at the time of transmitting a data frame, a video transmission apparatus stops the transmission of other packets. The video transmission apparatus then retransmits the packet that has not been transmitted until it is transmitted successfully. If the packet that has not been transmitted is not transmitted successfully after retransmission has been attempted a previously set number of times, a transmitting side retransmits the packet at a lowered packet transfer rate. If the packet is transmitted successfully through the above process, the video transmission apparatus transmits subsequent packets.
However, the conventional data transmission method emphasizes preserving the integrity of transmitted data by utilizing a specified bandwidth to the greatest extent. Accordingly, a problem arises because the conventional data transmission method does not use limited wireless network resources efficiently.
To solve the problem, several inventions, such as U.S. Patent Application Publication No. 2003-0005382 “System and Method for Frame Transmission in Broadcast Communication System,” have been proposed. However, the problem still remains unsolved.
In view of the above, there is a need for a data transmission method and apparatus which can efficiently use the limited resources of a wireless network at the time of transmitting video data over the wireless network.